In an era of too-good-to-be-true prices, gimmicky discounts and even an occasional zero fare, travelers have to make that call every day.

Sometimes they get it right. Sometimes not.

Last fall, for example, British Airways accidentally offered a $40 base fare from North America to India. After taxes and fees were added, the total came to around $500 — still a deal, but not an obvious error to the untrained eye. Thousands of people booked tickets in a two-hour period.

When British Airways refused to honor the price, many inexperienced air travelers were outraged. They pointed out that if the tables were turned — if they had made a mistake on their ticket — that the airline would keep their money.